If we believe that that Psalm 139:13-16 is true, then why do we have inherited diseases? The issue is the omnipotence and omniscience of Jehovah. If he knows that a person and / or animal will be born with a congenital disease, why not stop him if he can do so? Psalm 139:13-16 says, “For you created my inmost being; you knit me together in my mother’s womb. I praise You because I am fearfully and wonderfully made; Your works are wonderful. I know that full well. My frame was not hidden from You when I was made in the secret place, when I was woven together in the depths of the earth. Your eyes saw my unformed body; all the days ordained for me were written in Your book before one of them came to be.”
Sickness and disease are some of the results of sin. Instead of obeying God, and living forever without toil, struggle, sickness, and death, Adam chose to disobey God. When he sinned in the Garden of Eden, he brought death upon himself, and all mankind (Genesis 2:17, Genesis 3). He would now be subject to toil and struggle; aging; sickness; and, death (Genesis 3:17-19). God is indeed omnipotent, and He is just. If He had decided to let man die in his sin, with no hope of redemption, justice would have been served, as there would have been no payment for man’s sins. However, He put into place a plan of grace by which man can be redeemed through the blood of Christ on the cross (John 3:16). Believers will indeed live forever with God in eternity. However, meanwhile, we still have to finish this life in a sinful world, subject to sickness and disease.